<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

</body>

</html>
<script>
    var sum = 0
    for (i = 1; i < 101; i++) {
        if (i % 2 == 0) {
            sum -= (1 / i)
            // return sum;
        } else if(i%2==1) {
            sum += (1 / i)
            // return sum;
        }else {
            sum += (1 / i)
        }
        // sum += sum
    }
    console.log(sum);

</script>